From HTTP to Kafka-based Microservices (extended)

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FROM HTTP TO KAFKA-BASED FROM HTTP TO KAFKA-BASED MICROSERVICES MICROSERVICES (EXTENDED) (EXTENDED) Wojciech Rząsa, FLYR Poland @wrzasa From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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Informatics specialist by passion and by profession 15 years of academic work PhD but primarily an engineer FLYR Inc. Distributed systems Rzeszow Ruby User Group ABOUT ME ABOUT ME http://flyrlabs.com http://rrug.pl From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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FLYR FLYR Revenue management system for airlines Oﬀices in San Francisco, USA (PST) Kraków, Poland (CEST) Machine Learning Microservices Python GCloud Kubernetes Big Query From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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FLYR DEVS ON PYCON CZ FLYR DEVS ON PYCON CZ From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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IN FLYR MICROSERVICES IN FLYR MICROSERVICES IPC based on HTTP From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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IN FLYR MICROSERVICES IN FLYR MICROSERVICES IPC based on HTTP New requirements for eCommerce use case From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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FAN-OUT REQUESTS FAN-OUT REQUESTS From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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PARTIAL RESPONSES PARTIAL RESPONSES From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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PARTIAL RESPONSES PARTIAL RESPONSES From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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IN FLYR MICROSERVICES IN FLYR MICROSERVICES IPC based on HTTP New requirements for eCommerce use case partial responses From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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IN FLYR MICROSERVICES IN FLYR MICROSERVICES IPC based on HTTP New requirements for eCommerce use case partial responses performance From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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IN FLYR MICROSERVICES IN FLYR MICROSERVICES IPC based on HTTP New requirements for eCommerce use case partial responses performance We will need MQs anyway in the future From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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OK, LET'S SWITCH FROM HTTP OK, LET'S SWITCH FROM HTTP TO... A... MQ? TO... A... MQ? From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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BUT... BUT... From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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BUT... BUT... We have HTTP-based infrastructure From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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BUT... BUT... We have HTTP-based infrastructure We have HTTP developers experience and habits From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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BUT... BUT... We have HTTP-based infrastructure We have HTTP developers experience and habits We lack experience with MQ-based IPC From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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BUT... BUT... We have HTTP-based infrastructure We have HTTP developers experience and habits We lack experience with MQ-based IPC We need to do it well ;-) From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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WITH MQ WE GET WITH MQ WE GET Flexibility Reliability Scalability Robustness From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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NEW OPPORTUNITIES... NEW OPPORTUNITIES... From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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NEW OPPORTUNITIES... NEW OPPORTUNITIES... TO MAKE TO MAKE NEW MISTAKES NEW MISTAKES From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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NEW OPPORTUNITIES... NEW OPPORTUNITIES... TO MAKE TO MAKE NEW MISTAKES NEW MISTAKES Concurrency issues From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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NEW OPPORTUNITIES... NEW OPPORTUNITIES... TO MAKE TO MAKE NEW MISTAKES NEW MISTAKES Concurrency issues Race conditions From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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NEW OPPORTUNITIES... NEW OPPORTUNITIES... TO MAKE TO MAKE NEW MISTAKES NEW MISTAKES Concurrency issues Race conditions Incorrect broker choice From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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NEW OPPORTUNITIES... NEW OPPORTUNITIES... TO MAKE TO MAKE NEW MISTAKES NEW MISTAKES Concurrency issues Race conditions Incorrect broker choice Incorrect driver for the correct broker From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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NEW OPPORTUNITIES... NEW OPPORTUNITIES... TO MAKE TO MAKE NEW MISTAKES NEW MISTAKES Concurrency issues Race conditions Incorrect broker choice Incorrect driver for the correct broker Incorrect usage patterns for the correct driver From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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NEW OPPORTUNITIES... NEW OPPORTUNITIES... TO MAKE TO MAKE NEW MISTAKES NEW MISTAKES Concurrency issues Race conditions Incorrect broker choice Incorrect driver for the correct broker Incorrect usage patterns for the correct driver Incorrect usage patterns for the correct broker From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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NEW OPPORTUNITIES... NEW OPPORTUNITIES... TO MAKE TO MAKE NEW MISTAKES NEW MISTAKES Concurrency issues Race conditions Incorrect broker choice Incorrect driver for the correct broker Incorrect usage patterns for the correct driver Incorrect usage patterns for the correct broker . . . From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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LET'S CONTAIN THE RISKS IN LET'S CONTAIN THE RISKS IN ONE PLACE ONE PLACE From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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LET'S CONTAIN THE RISKS IN LET'S CONTAIN THE RISKS IN ONE PLACE ONE PLACE (A LIBRARY) (A LIBRARY) From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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AND CALL THIS PLACE AND CALL THIS PLACE async_calls async_calls From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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AND CALL THIS PLACE AND CALL THIS PLACE async_calls async_calls (FOR THE LACK OF BETTER CONCEPT) (FOR THE LACK OF BETTER CONCEPT) From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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A LIBRARY THAT A LIBRARY THAT meets functional requirements for developers, resembles HTTP where possible uses a MQ broker for communication From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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FOR MAINTAINERS FOR MAINTAINERS THE SAURON ADVANTAGE :) THE SAURON ADVANTAGE :) From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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FOR MAINTAINERS FOR MAINTAINERS THE SAURON ADVANTAGE :) THE SAURON ADVANTAGE :) From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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FOR MAINTAINERS FOR MAINTAINERS THE SAURON ADVANTAGE :) THE SAURON ADVANTAGE :) One place to fix them all (bugs) One place to change them all (decisions about broker, drivers, ...) One place to apply them all (correct usage patters) From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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FOR DEVELOPERS FOR DEVELOPERS New complexity is hidden Lower entry barrier From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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DECISIONS DECISIONS From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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DECISIONS DECISIONS Message Broker – Kafka performance persistence From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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DECISIONS DECISIONS Message Broker – Kafka performance persistence Kafka driver – confluent-kafka performance supported by Confluent From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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ASSUMPTIONS ASSUMPTIONS Make it simple – provide just IPC Library, not framework approach Make it testable manually (curl-like tool) automatically (reasonable mocks) Make it resemble Flask? From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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TALK IS CHEAP! TALK IS CHEAP! From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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CREATE AN APPLICATION OBJECT CREATE AN APPLICATION OBJECT from async_calls import AsyncCalls async_calls = AsyncCalls('a-money-broker') From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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CREATE AN APPLICATION OBJECT CREATE AN APPLICATION OBJECT CREATE A BASIC ENDPOINT CREATE A BASIC ENDPOINT from async_calls import AsyncCalls async_calls = AsyncCalls('a-money-broker') @async_calls.server.callback_for('/show-me-the-money') def show_me_the_money(request): for i in range(1,5): payload = f"Response {i} for call: {request.id}" response = request.create_response(payload) async_calls.server.send(response) time.sleep(1) From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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CREATE AN APPLICATION OBJECT CREATE AN APPLICATION OBJECT CREATE A BASIC ENDPOINT CREATE A BASIC ENDPOINT from async_calls import AsyncCalls async_calls = AsyncCalls('a-money-broker') # a service ID @async_calls.server.callback_for('/show-me-the-money') def show_me_the_money(request): for i in range(1,5): payload = f"Response {i} for call: {request.id}" response = request.create_response(payload) async_calls.server.send(response) time.sleep(1) From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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CREATE AN APPLICATION OBJECT CREATE AN APPLICATION OBJECT CREATE A BASIC ENDPOINT CREATE A BASIC ENDPOINT from async_calls import AsyncCalls async_calls = AsyncCalls('a-money-broker') # a service ID @async_calls.server.callback_for('/show-me-the-money') def show_me_the_money(request): # ^^^^^^^^ an endpoint name for i in range(1,5): payload = f"Response {i} for call: {request.id}" response = request.create_response(payload) async_calls.server.send(response) time.sleep(1) From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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CREATE A BASIC CLIENT CREATE A BASIC CLIENT request = async_calls.client.new_message( destination_service_id: 'a-money-broker', target_endpoint: '/show-me-the-money', request_payload ) async_calls.client.send(request) From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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CREATE A BASIC CLIENT CREATE A BASIC CLIENT @async_calls.client.callback_for( 'a-money-broker', '/show-me-the-money') def the_money_handler(response): logger.info( f"Got: {response.id} for: {response.referenced_id}" ) request = async_calls.client.new_message( destination_service_id: 'a-money-broker', target_endpoint: '/show-me-the-money', request_payload ) async_calls.client.send(request) From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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TO START LISTENING TO START LISTENING (CLIENT AND SERVER) (CLIENT AND SERVER) async_calls.listen() From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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WHAT WE HAVE THEN? WHAT WE HAVE THEN? From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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WHAT WE HAVE THEN? WHAT WE HAVE THEN? Server — event-driven (like HTTP) From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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WHAT WE HAVE THEN? WHAT WE HAVE THEN? Server — event-driven (like HTTP) Client — non-blocking, event-driven (unlike HTTP) From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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WHAT WE HAVE THEN? WHAT WE HAVE THEN? Server — event-driven (like HTTP) Client — non-blocking, event-driven (unlike HTTP) One request — any number of responses From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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WHAT WE HAVE THEN? WHAT WE HAVE THEN? Server — event-driven (like HTTP) Client — non-blocking, event-driven (unlike HTTP) One request — any number of responses A single process can be a server and a client From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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HOW DO WE TEST THIS!? HOW DO WE TEST THIS!? From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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async_calls async_calls HAS A TESTING MODE HAS A TESTING MODE From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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TESTING A SERVER TESTING A SERVER DOES IT RESPOND CORRECTLY? DOES IT RESPOND CORRECTLY? From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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TESTING A CLIENT TESTING A CLIENT DOES IT SEND EXPECTED REQUESTS? DOES IT SEND EXPECTED REQUESTS? From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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TESTING CLIENT TESTING CLIENT FAKING SERVER'S RESPONSE FAKING SERVER'S RESPONSE From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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TESTING SUMMARY TESTING SUMMARY Tools out-of-the-box Calls made on stack, deterministic tests No MQ broker required for unittests No need to think about IPC details when implementing tests From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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MANY MORE FEATURES MANY MORE FEATURES before send and before receive hooks (e.g. for validations) endpoint context managers (e.g. for performance measurements) endpoint error handlers Kubernetes healthcheck CLI curl-like client From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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ANY DRAWBACKS? ANY DRAWBACKS? Hiding complexity we hide opportunities... ...not only to make new errors e.g. no Kafka Streams via async_calls From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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HOW DID IT SAVE US? HOW DID IT SAVE US? Concurrency issues Race conditions Incorrect broker choice Incorrect driver for the correct broker Incorrect usage patterns for the correct driver Incorrect usage patterns for the correct broker . . . From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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SUMMARY SUMMARY Switching from HTTP to async_calls Server is straightforward Client is not complicated From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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SUMMARY SUMMARY Switching from HTTP to async_calls Server is straightforward Client is not complicated Support for one-way communication From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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SUMMARY SUMMARY Switching from HTTP to async_calls Server is straightforward Client is not complicated Support for one-way communication More complex use cases require more attention Services are easily testable From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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SUMMARY SUMMARY Switching from HTTP to async_calls Server is straightforward Client is not complicated Support for one-way communication More complex use cases require more attention Services are easily testable Standard project-wide layer for asynchronous IPC From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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SUMMARY SUMMARY Switching from HTTP to async_calls Server is straightforward Client is not complicated Support for one-way communication More complex use cases require more attention Services are easily testable Standard project-wide layer for asynchronous IPC A number of small but useful bonuses From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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ASYNCHRONOUS WAR STORIES ASYNCHRONOUS WAR STORIES From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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SERVICES SERVICES From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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FAILURES AND ERRORS FAILURES AND ERRORS From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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SERVICES – HAPPY PATH SERVICES – HAPPY PATH From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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COMMUNICATION ASSUMPTIONS COMMUNICATION ASSUMPTIONS Deduplication (using version on each record) Version checking on >= version not on == version + 1 Error in code causes exception Exception prevents committing of Kafka message From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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SERVICES – FAILURE 1 SERVICES – FAILURE 1 From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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SERVICES – FAILURE 2 SERVICES – FAILURE 2 From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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SERVICES – FAILURE 3 SERVICES – FAILURE 3 From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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MESSAGE (RE)ORDERING MESSAGE (RE)ORDERING From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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MESSAGE ORDER OK MESSAGE ORDER OK From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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MESSAGE ORDER CHANGED MESSAGE ORDER CHANGED From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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ASYNCHRONOUS (REST-LIKE) CRUD ASYNCHRONOUS (REST-LIKE) CRUD From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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ASYNCHRONOUS (REST-LIKE) ASYNCHRONOUS (REST-LIKE) CRUD CRUD From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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DELETE CANNOT DELETE? DELETE CANNOT DELETE? From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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DELETE SHOULD CREATE? DELETE SHOULD CREATE? From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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PATCH? PATCH? From HTTP to Kafka-based Microservices – [email protected] – @wrzasa

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SUMMARY SUMMARY A library hiding MQ from devs works well Cannot hide all async problems behind a facade Consequences in DB design Decisions dependent on business logic HTTP to MQ is not just a change of transport Procedures of restoring data consistency Do I really need all this mess? From HTTP to Kafka-based Microservices – [email protected] – @wrzasa